We think of "restaurant food" as fancy or complicated, but that's far from always true. Fish and chips is as unfussy as good food gets, yet it's a definitive example of restaurant food, because you can't really cook proper fish and chips at home – or, rather, you can, but with such an investment in gear, expertise and effort that you won't be doing much of anything else. No, Britain's national dish – unlike that of any other country I know – is best encountered in a restaurant.

That restaurant has a short list of things it needs to get right. It has to source good fresh fish – much harder than it has any right to be. The fish has to be carefully battered and fried to order – again, easy to say but hard to do, given the unpredictable rushes of punters demanding their grub right now. Then they have to cook the chips, ideally and classically twice, once on lower heat to cook through and once on high for crunch. This adds up to a fairly demanding wishlist, and so we shouldn't be surprised when so many chippies are only there and thereabouts. When they are spot on, we should celebrate them.

Here's one: the Fish Shed at Dart's Farm just outside Exeter. The farm is one of Britain's oldest pick-your-owns, and if that leads you to expect something cozy and pleasantly shabby at the edges, something that might trigger a Good Life flashback, you're dead wrong, because Dart's Farm is now a large, glitzy complex, including shops where you can buy tiles, or kitchenware, or indeed an Aga, as well as the large, beautifully presented spread of fresh produce that is still the centrepiece of the operation. (The Aga shop prompted me to wonder if anyone ever bought one on impulse. "Honey, surprise!") A whole stand of lettuce picked that morning – what's not to love? There were also posters offering free Mercedes test drives that coming weekend – what's not to hate?

Off to one side is the Fish Shed. As the name implies, it is a shed where they cook fish, rather than a formal restaurant. A bit of it is under cover, but not all, and much of the place is protected by nothing but umbrellas. In inclement weather, that would be an issue, and let's face it, it does sometimes rain in the West Country.

The Fish Shed has this simple and wonderful policy: it sells only fish caught that day and landed in Lyme Bay. (It sells wet fish, too, so as well as being a brilliant chippie, it's also a brilliant fish shop.) This obviously means that the daily offer will vary. I had fancied the lobster, which they sometimes have on, but – waaah! – not that day. They did have dover sole and it was beautiful, filleted and grilled simply. It's a hard dish to beat.

But you can't go to a chippie and not have fried fish. The haddock was as good as it gets, the flesh moist and dense, the batter satisfyingly thick but also crunchy and light. Overall, it had the perfect texture and density. I have a pet theory that English batter of this sort gave the Portuguese the idea, which they (this part is historically attested) gave to the Japanese in the form of tempura. With batter this good, that theory seems plausible. A younger member of our family had battered sausages, and they were awesome, too, in their fun-food, don't-try-this-at-home way.

The defining issue for any chippie, however, is the chips. Those here were top-notch, and proper British chips, too, thick and potatoey, as well as crunchy to the bite, irregular in cut and full of flavour. The crunchiness was aided by the fact that they're cooked in beef dripping, which has a higher burning point and so makes crisper chips. (They'll do them in oil, if you prefer.) Greed warning: the chip portions aren't huge.

The restaurant isn't licensed, but there is a wine shop only a few feet away inside the Dart's Farm complex. The logical thing to do would be to buy a bottle there. If the shop had a fridge, it would be perfect, but it doesn't, which is a humanitarian tragedy, unless you a) prefer red with fish; b) prefer room temperature white; c) don't drink; or d) don't care. The last option is probably the best, because wine and batter go together like Doherty and Barat.